[Lldb-commits] [lldb] r106045 - /lldb/trunk/include/lldb/Core/dwarf.h

[Jason Molenda]

OK I'll look over the use of the printers in llvm tomorrow and make sure we don't get double DW_'s anywhere. ;)

Thanks,

J

On Jun 15, 2010, at 11:29 PM, Chris Lattner wrote:

> FWIW, I agree with Devang.  It would be nice to have the various dwarf constants all localized.  Imagine a world where the compiler and debugger agree on purpose instead of by accident! :)
> 
> -Chris
> 
> 
> On Jun 15, 2010, at 11:26 PM, Devang Patel wrote:
> 
>> On Tue, Jun 15, 2010 at 8:27 PM, Jason Molenda <jmolenda at apple.com> wrote:
>>> 
>>> On Jun 15, 2010, at 2:43 PM, Chris Lattner wrote:
>>> 
>>>> Can Core/dwarf.h use (and extend) llvm/include/llvm/Support/Dwarf.h instead of duplicating much of it?
>>> 
>>> Yeah, I can do that.  I need to add the full set of DW_OP_{lit,reg,breg}{0..31} constants to include/llvm/Support/Dwarf.h and lib/Support/Dwarf.cpp at the very least.  The printers over in Dwarf.cpp are a little annoying - the DW_TAG ones include the "DW_" prefix, the rest do not.  It always grates one me when I see the prefix missing in program output - I have yet to see a context where the extra three characters would have killed anyone.  I'm adding functions like
>>> 
>>> const char *
>>> DW_ACCESS_value_to_name (uint32_t val)
>>> {
>>> static char invalid[100];
>>> const char *llvmstr = AccessibilityString (val);
>>> if (llvmstr == NULL)
>>> {
>>>     snprintf (invalid, sizeof (invalid), "Unknown DW_ACCESS constant: 0x%x", val);
>>>     return invalid;
>>> }
>>> 
>>> std::string str;
>>> if (strlen (llvmstr) < 3 || llvmstr[0] != 'D' || llvmstr[1] != 'W' || llvmstr[2] != '_')
>>>   str = "DW_";
>>> str += llvmstr;
>>> ConstString const_str (str.c_str());
>>> 
>>> return const_str.GetCString();
>>> }
>> 
>> Instead of doing this, feel free to update llvm/lib/Support/Dwarf.cpp
>> printer routines to use DW_ prefix.
>> 
>>> to lldb's DWARFDefines.cpp to compensate.  We also have a "value to englishy name" utility function that removes all prefix chars (e.g. "DW_FORM_") and changes '_'s to ' ' for printing; they're used in a few places.  To reimplement those on top of the llvm printers I needed to add the modified string to lldb's const string pool and return a pointer to that.  But for the simple value_to_name printers, it's a lot of extra fussing about to ensure that the strings have "DW_" at the front.
>>> 
>>> 
>>> In general I prefer the generated approach used for the header/printer functions in lldb -- there is a text file like
>>> 
>>> /* START: [7.5.4] Figure 16 "Tag Encodings" (pp. 125-127) in DWARFv3 draft 8 */
>>> /* PREFIX: DW_TAG */
>>> /* VALIDATTRIBS: DWARFv3 */
>>> 
>>> array_type 0x01
>>> class_type 0x02
>>> entry_point 0x03
>>> enumeration_type 0x04
>>> formal_parameter 0x05
>>> imported_declaration 0x08
>>> label 0x0a
>>> lexical_block 0x0b
>>> member 0x0d
>>> pointer_type 0x0f
>>> 
>>> etc. so that only one table is maintained.  A simple script emits the header file and C source file that prints the texts.  In practice the contents change so rarely that it's not a big deal.
>>> 
>>> 
>>> OK to check in the additional constant values to llvm?
>> 
>> Sure, feel free to add new constants in llvm/include/llvm/Support/Dwarf.h
>> 
>> -
>> Devang
> 
> 
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